IP (Internet Protocol) is the development trend of future network services, and Ethernet has become the main development direction of IP-based bearer network with its excellent cost performance, widespread application and product support.
When deploying a carrier-class Ethernet, time synchronization and clock synchronization of a device is a key performance indicator. In the communication network, different services have different requirements on time synchronization, for example, services such as billing systems, communication network management systems and VII signaling usually require millisecond time synchronization. Wherein, the most stringent requirement comes from mobile network services, and, with the development of mobile technology, mobile network services also have higher and higher requirements on precision and reliability of time synchronization of network.
For implementing transmission of time synchronization signals in the Ethernet, at present a class of relatively mature technologies is the packet-based synchronization technology, for example, the time synchronization technology implemented based on the IEEE 1588 V2 protocol (that is, Precision Time Protocol, referred to as PTP).
The time synchronization technology implemented based on the IEEE 1588 V2 protocol can usually achieve time precision of sub-microsecond and even nanosecond level. As shown in FIG. 1, it is required to send IEEE 1588 V2 protocol packets between the master device and the slave device, and the packets respectively carry time information, and on the slave device side, according to the time information in a group of IEEE 1588 V2 protocol packets, the Time Offset between the slave device and the master device can be calculated out to correct the time of the slave device, so as to achieve time synchronization. FIG. 1(a) is a flow chart of a group of packets based on the E2E (End-to-End) synchronization mechanism in the IEEE 1588 V2 protocol as well as time synchronization; FIG. 1(b) is a flow chart of a group of packets based on the P2P (Peer-to-Peer) synchronization mechanism in the IEEE 1588 V2 protocol as well as time synchronization.
The reliability of time synchronization technology achieved based on the IEEE 1588 V2 protocol is relatively poor, and when a protocol packet loss caused by abnormalities such as an abnormal link or a congestion between the master device and the slave device occurs, it may result in an incomplete sequence in a group of protocol packets, thereby causing time synchronization failure.
For the abovementioned problem, so far no effective solutions have been proposed yet.